MEMS resettable timer

• US 7,398,734 B1
• Filed: 03/09/2006
• Issued: 07/15/2008
• Est. Priority Date: 03/09/2006
• Status: Expired due to Fees

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Jean, Daniel L.
• Primary Examiner(s): HAYES, BRET C
• Application Number:
  US11/374,482
• Time in Patent Office: 859 Days
• Field of Search: 102231-233, 102247-249, 102/264, 102/275.11, 102/276
• US Class Current: 102/249
• CPC Class Codes: F42C 15/24 wherein the safety or arming action is effected by inertia means F42C15/196, F42C15/20 take precedence

Abstract

A MEMS resettable timer including a primary inertial element and at least one secondary inertial element, which includes a camming surface. When the secondary inertial element moves, its camming surface engages the camming surface of a locking element to remove it from the notch of a subsequent inertial element. When the primary inertial element is released for movement it activates a resetting arrangement to place the secondary inertial element back to the initial position and prevent further movement of the primary inertial element. The cycle is repeatable to commence some predetermined action.

Claims

1. A resettable timer, comprising:

a primary inertial element, said primary inertial element including a plurality of sequentially arranged locking notches and a plurality of sequentially arranged camming surfaces;

at least one secondary inertial element being at an initial position;

a locking element being positioned within a first of said plurality of sequentially arranged locking notches to prevent movement of said primary inertial element, said locking element comprising a camming surface,

wherein said at least one secondary inertial element includes a camming surface positioned to engage said camming surface of said locking element, in a first cycle, upon a repositioning of said secondary inertial element due to an acceleration of said timer, to withdraw said locking element from said first of said plurality of sequentially arranged locking notches;

a reset bar comprising a camming surface, said reset bar operable to reset said secondary inertial element to said initial position;

a reset activation member comprising a first camming surface, which engages with a first of said plurality of sequentially arranged camming surfaces of said primary inertial element and a second camming surface engageable with said camming surface of said reset bar,

wherein when said locking element is withdrawn, said primary inertial element is moved out of position causing said reset activation member to move said reset bar to reset said secondary inertial element to said initial position, and

wherein said resetting causes said locking element to position itself in the next of said sequentially arranged locking notches and said first camming surface of said reset activation member to position itself adjacent a second of said sequentially arranged camming surfaces to repeat said cycle until said primary inertial element is no longer restrained from movement;

a plurality of supports; and

a plurality of springs connecting said primary inertial element, said at least one secondary inertial element, said locking element, said reset bar and said reset activation member to respective ones of said plurality of supports,

wherein said resettable timer is a MEMS timer device.

2. The timer according to claim 1, wherein a mass of said primary inertial element is greater than a mass of said at least one secondary inertial element.

3. The timer according to claim 1, wherein all of said camming surfaces are linear camming surfaces.

4. A resettable timer, comprising:

a primary inertial element, said primary inertial element comprising a plurality of sequentially arranged locking notches and a plurality of sequentially arranged camming surfaces;

a plurality of secondary inertial elements, each at an initial position,

wherein each of said plurality of secondary inertial element comprising a camming surface being on one side thereof and at least all but a first of said plurality of secondary inertial elements comprising a locking notch on an opposite side thereof,

a plurality of locking elements each comprising a camming surface, a first of said plurality of locking elements being positioned between a first and a second of said plurality of secondary inertial elements and initially engaging a locking notch of said second of plurality of secondary inertial elements,

wherein subsequent ones of said plurality of locking elements being positioned between subsequent ones of said plurality of secondary inertial elements and engaging the locking notch of a subsequent of said plurality of secondary inertial elements, a last of said plurality of locking elements engaging the first of said plurality of sequentially arranged locking notches of said primary inertial element to prevent movement thereof,

wherein said camming surface of a first of said plurality of secondary inertial elements is operable to engage said camming surface of a first locking element of said plurality of said locking elements, in a first cycle, upon a repositioning of said first of said plurality of secondary inertial elements due to an acceleration of said resettable timer, to withdraw said first locking element from said locking notch of a second of said plurality of secondary inertial elements, and

wherein said camming surface of said subsequent of said plurality of secondary inertial elements engaging said camming surfaces of said subsequent ones of said locking elements, with said last of said locking elements is withdrawn from said first of said sequentially arranged locking notches of said primary inertial element in said first cycle;

a reset bar comprising a camming surface, said reset bar operable to reset all of said plurality of secondary inertial elements to their said initial position;

a reset activation member comprising a first camming surface, which engages with a first of said plurality of sequentially arranged camming surfaces of said primary inertial element and a second camming surface engageable with said camming surface of said reset bar,

wherein when said locking element is withdrawn from said first locking notch of said primary inertial element, said primary inertial element moves out of position causing said reset activation member to move said reset bar to reset said all of said secondary inertial elements to their said initial positions, and

wherein said resetting causes said last of said plurality of locking elements to position itself in the next of said sequentially arranged locking notches and said First camming surface of said reset activation member to position itself adjacent a second of said sequentially arranged camming surfaces to repeat said cycle until said primary inertial element is no longer restrained from movement;

a plurality of supports; and

a plurality of springs connecting said primary inertial element, said plurality of secondary inertial elements, said plurality of locking elements, said reset bar and said reset activation member to respective ones of said plurality of supports,

wherein said resettable timer is a MEMS timer device.

5. The timer according to claim 4, wherein a mass of said primary inertial element is greater than masses of each of said plurality of secondary inertial elements.

6. The timer according to claim 4, wherein the mass of said primary inertial element is greater than a total mass of all said plurality of secondary inertial elements.

7. A timer, comprising:

a primary inertial element;

a plurality of secondary inertial elements being at an initial position;

a locking arrangement for preventing movement of all but a first inertial element of said plurality of secondary inertial elements; and

a reset arrangement,

wherein movement of said first inertial element, due to an acceleration of said timer, is operable to commence an unlocking of said locking arrangement to allow sequential movement of said plurality of secondary inertial elements and said primary inertial element,

wherein movement of said primary inertial element activates said reset arrangement to place said plurality of secondary inertial elements back to said initial positions, in a first cycle, and prevent further movement of said primary inertial element,

wherein said cycle repeating itself at least one more time with continued acceleration until said primary inertial element is no longer restrained from movement, and

wherein said timer is a MEMS timer device.

8. A timer, comprising:

,

a primary inertial element;

a plurality of secondary inertial elements at an initial position;

a locking arrangement where said primary inertial element and said plurality of secondary inertial elements are locked except a first inertial element of said plurality of secondary inertial elements; and

a reset arrangement,

wherein said plurality of said secondary inertial elements are intermediate said first inertial element and said primary inertial element,

wherein a movement of said first inertial element sequentially unlocks said plurality of secondary inertial elements and said primary inertial element before said primary inertial element contacts said reset arrangement, which resets said plurality of secondary elements back to said initial position, and

wherein said timer is a MEMS timer device.

9. The timer according to claim 8, wherein said primary inertial element and said plurality of secondary inertial elements are substantially parallel to each other.

10. The timer according to claim 8, wherein said locking arrangement comprises a plurality of locking elements.

11. The timer according to claim 10, wherein one of said plurality of locking elements is intermediate said primary inertial element and one of said plurality of secondary inertial elements.

12. The timer according to claim 10, wherein each of said plurality of secondary inertial elements is separated from another by a locking element of said plurality of locking elements.

13. The timer according to claim 8, wherein said timer is a resettable timer due to said movement of said primary inertial element, said plurality of secondary inertial elements, said locking arrangement and said reset arrangement.

14. A timer, comprising:

a primary inertial element;

at least one secondary inertial element at an initial position;

a locking arrangement intermediate said primary inertial element and said at least one secondary inertial element;

a reset arrangement,

wherein said reset arrangement is substantially adjacent said primary inertial element and said at least one secondary inertial element,

wherein acceleration of said timer causes said reset arrangement to move said at least one secondary element back to said initial position and inhibit movement of said primary inertial element, and

wherein said timer is a MEMS timer device.

15. The timer according to claim 14, wherein said reset arrangement is comprised of a reset bar and a reset activation member.